// ConsoleTools
// Copyright (C) 2017-2024 Dust in the Wind
// 
// This program is free software: you can redistribute it and/or modify
// it under the terms of the GNU General Public License as published by
// the Free Software Foundation, either version 3 of the License, or
// (at your option) any later version.
// 
// This program is distributed in the hope that it will be useful,
// but WITHOUT ANY WARRANTY; without even the implied warranty of
// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
// GNU General Public License for more details.
// 
// You should have received a copy of the GNU General Public License
// along with this program.  If not, see <http://www.gnu.org/licenses/>.

// --------------------------------------------------------------------------------
// Bugs or feature requests
// --------------------------------------------------------------------------------
// Note: For any bug or feature request please add a new issue on GitHub: https://github.com/lastunicorn/ConsoleTools/issues/new/choose

using System;
using System.Collections.Generic;
using System.Text;

namespace DustInTheWind.ConsoleTools.Controls.Tables;

/// <summary>
/// Builds the border that separates two rows.
/// </summary>
internal class HorizontalSeparatorBuilder
{
    private StringBuilder sb;

    private int topIndex;
    private int bottomIndex;

    private int topWidth;
    private int bottomWidth;

    private bool topWidthEnded;
    private bool bottomWidthEnded;

    /// <summary>
    /// Gets the character used to render an internal horizontal border.
    /// </summary>
    public char Horizontal { get; set; }

    /// <summary>
    /// Gets the character used to render the intersection between the top outer border and an internal vertical border.
    /// </summary>
    public char TopIntersection { get; set; }

    /// <summary>
    /// Gets the character used to render the intersection between the right outer border and an internal horizontal border.
    /// </summary>
    public char RightIntersection { get; set; }

    /// <summary>
    /// Gets the character used to render the intersection between the bottom outer border and an internal vertical border.
    /// </summary>
    public char BottomIntersection { get; set; }

    /// <summary>
    /// Gets the character used to render the intersection between the left outer border and an internal horizontal border.
    /// </summary>
    public char LeftIntersection { get; set; }

    /// <summary>
    /// Gets the character used to render the intersection between two internal borders: a vertical and a horizontal one.
    /// </summary>
    public char MiddleIntersection { get; set; }

    /// <summary>
    /// Gets the character used to render the top right corner.
    /// </summary>
    public char TopRight { get; set; }

    /// <summary>
    /// Gets the character used to render the bottom right corner.
    /// </summary>
    public char BottomRight { get; set; }

    public IList<int> TopCellWidths { get; set; }

    public IList<int> BottomCellWidths { get; set; }

    public string Build()
    {
        if (TopCellWidths == null)
            throw new ApplicationException("TopCellWidths must be provided.");

        if (BottomCellWidths == null)
            throw new ApplicationException("BottomCellWidths must be provided.");

        if (TopCellWidths.Count == 0 && BottomCellWidths.Count == 0)
            return string.Empty;

        Start();

        while (true)
        {
            if (topWidthEnded)
                AddBottomCell();
            else if (bottomWidthEnded)
                AddTopCell();
            else if (topWidth < bottomWidth)
                AddTopCell();
            else if (bottomWidth < topWidth)
                AddBottomCell();
            else
                AddBothCells();

            if (topWidth == 0 && bottomWidth == 0)
                break;
        }

        return sb.ToString();
    }

    private void Start()
    {
        sb = new StringBuilder();

        topIndex = -1;
        bottomIndex = -1;

        topWidthEnded = false;
        bottomWidthEnded = false;

        sb.Append(LeftIntersection);

        NextTopWidth();
        NextBottomWidth();
    }

    private void AddTopCell()
    {
        sb.Append(new string(Horizontal, topWidth));

        if (bottomWidthEnded)
        {
            sb.Append(BottomRight);
        }
        else
        {
            sb.Append(BottomIntersection);
            DecreaseBottom(topWidth + 1);
        }

        NextTopWidth();
    }

    private void DecreaseBottom(int value)
    {
        bottomWidth = Math.Max(bottomWidth - value, 0);
    }

    private void AddBottomCell()
    {
        sb.Append(new string(Horizontal, bottomWidth));

        if (topWidthEnded)
        {
            sb.Append(TopRight);
        }
        else
        {
            sb.Append(TopIntersection);
            DecreaseTop(bottomWidth + 1);
        }

        NextBottomWidth();
    }

    private void DecreaseTop(int value)
    {
        topWidth = Math.Max(topWidth - value, 0);
    }

    private void AddBothCells()
    {
        sb.Append(new string(Horizontal, topWidth));

        if (IsLastTop() && IsLastBottom())
            sb.Append(RightIntersection);
        else
            sb.Append(MiddleIntersection);

        NextTopWidth();
        NextBottomWidth();
    }

    private bool IsLastTop()
    {
        return topIndex + 1 == TopCellWidths.Count;
    }

    private bool IsLastBottom()
    {
        return bottomIndex + 1 == BottomCellWidths.Count;
    }

    private void NextTopWidth()
    {
        if (topIndex + 1 < TopCellWidths.Count)
        {
            topIndex++;
            topWidth = TopCellWidths[topIndex];
        }
        else
        {
            topWidth = 0;
            topWidthEnded = true;
        }
    }

    private void NextBottomWidth()
    {
        if (bottomIndex + 1 < BottomCellWidths.Count)
        {
            bottomIndex++;
            bottomWidth = BottomCellWidths[bottomIndex];
        }
        else
        {
            bottomWidth = 0;
            bottomWidthEnded = true;
        }
    }
}